1. Field
An embodiment of the invention relates to a head used in a disk drive such as a magnetic disk drive, head suspension assembly provided with the head, and disk drive provided with the head suspension assembly.
2. Description of the Related Art
A disk drive, e.g., a magnetic disk drive, includes a magnetic disk, spindle motor, magnetic head, and carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the disk. The magnetic head writes and reads information to and from the disk. The carriage assembly supports the head for movement with respect to the disk. The carriage assembly includes a rotatably supported arm and a suspension extending from the arm. The magnetic head is supported on an extended end of the suspension. The head includes a slider attached to the suspension and a head portion on the slider. The head portion includes a reproducing element for reading and a recording element for writing.
The slider has a disk-facing surface or air bearing surface (ABS) opposed to a recording surface of the magnetic disk. A predetermined head load directed to a magnetic recording layer of the disk is applied to the slider by the suspension. When the magnetic disk drive operates, airflows are produced between the disk in rotation and the slider. Based on the principle of aerodynamic lubrication, a force (positive pressure) to fly the slider above the recording surface of the disk acts on the ABS of the slider. By balancing this flying force with the head load, the slider is flown with a gap above the recording surface of the disk. Jpn. Pat. Appln. KOKAI Publication No. 2007-73165, e.g., discloses a disk drive in which a negative-pressure cavity or dynamic-pressure generating groove is formed near the center of a facing surface of a slider in order to prevent variation of the flying height of the slider.
The slider includes the negative-pressure cavity formed at the central part of an ABS, a front pad portion formed on the air inflow-end side of the slider, and rear pad portion on the air outflow-end side of the slider. The rear pad portion is composed of an outflow-side step portion, outflow-side rail face continuous with the outflow-side step portion, groove deeper than the rail face, and outflow-side pad portion flush with the rail face. The front and opposite sides of the outflow-side pad portion are surrounded by the outflow-side rail face. A magnetic transducer that constitutes the head portion is provided on the outflow-side pad portion.
Airflows between the disk surface and the ABS of the slider produce positive pressures at the front pad portion, rear pad portion, and outflow-side pad portion. Thereupon, the slider maintains a flying posture in which the outflow-side pad portion is located closest to the disk surface.
A discrete track recording (DTR) disk has recently been provided as a magnetic disk with improved recording density. In this magnetic disk, grooves are formed between adjacent tracks so that interference between the adjacent tracks is reduced.
In writing or reading information to or from a rugged recording surface of the DTR disk by using the magnetic head described above, the positive pressures produced at the individual pad portions of the slider change due to variation of irregularities of the recording surface or fine dust produced as media are machined. In consequence, the flying height of the slider varies considerably. The pressure produced at the outflow-side pad portion that is located closest to the disk surface is particularly liable to variation. If the flying height of the slider varies in this manner, it is difficult to stably record and reproduce information on and from the disk.